1. Field of the Invention
The present invention relates to a method of efficiently fabricating a low-cost phased array. More specifically, the present invention relates to a multilayer phased array and method of fabrication thereof, using low temperature co-fired ceramic (LTCC)— based layers, some of which are micro-electromechanical system (MEMS) layers.
2. Background of the Invention
In the related art, micro-electromechanical system (MEMS) technology integrates the silicon substrate of printed-circuit and computer technologies with tiny mechanical devices. For example, but not by way of limitation, MEMS technology may include sensors, valves, gears, mirrors, switches or actuators embedded in semiconductor devices.
While the related art electronics of MEMS devices are fabricated via an Integrated Circuit (IC) process, the micromechanical MEMS components are fabricated by a micromachining process that selectively etches or adds layers to form the MEMS device. Once produced, the micromechanical components form sensory and mechanical parts of a MEMS device, while the electronics part forms the “brain” of a MEMS device. Accordingly, MEMS combines the computational ability of microelectronics with control capabilities of microsensors and microactuators. In related art communications systems, the combination of silicon and micromachining allows for very high bandwidth mechanical devices.
Related art MEMS devices are manufactured using techniques that are substantially similar to the related art IC fabrication processes. For example, but not by way of limitation, a batch fabrication process may be used to make a MEMS device.
The modular concept of multilayer active phased arrays is the subject of co-pending International Application No. PCT/US02/03379, filed Feb. 14, 2002, which discloses the contents of the integrated module that contains radiating elements, polarizing circuits, power dividing networks and filters. The radiating elements are electromagnetically coupled patches, and the polarizing circuits are hybrid couplers that provide the phase quadrature needed to produce circular polarizations. The phase shifters and other components can be implemented using MEMS technology. Although the invention disclosed in the above-mentioned International Application No. PCT/US02/03379 reduces the cost of making the active phased arrays due to the modularity of the design and the use of lower loss MEMS components, the production costs are still prohibitive for some applications.
The aforementioned related art has various problems and disadvantages. For example, but not by way of limitation, it is a disadvantage of the related art MEMS fabrication process that IC packaging processes must be used for manufacture of MEMS devices. As noted above, there are substantial structural and functional differences between IC and MEMS, including the need for MEMS to be manufactured in substantially continuous and intimate contact with their environment. Thus, the related art MEMS fabrication process is not efficient
Further, in the related art, a new, specialized package must be created each time a new MEMS device is developed, at an additional time and financial cost. As a result, the related art MEMS fabrication process has another disadvantage and is one of the most expensive aspects of MEMS product development, as there are no related art standardized packages from which one would be able to choose a MEMS package for a new application without substantially compromising performance.
Also, the related art fabrication process has another disadvantage, due to its complexity, and requires a substantial research investment to generate a suitable fabrication sequence. Because the design is dependent on the fabrication, there is an additional cost in that process-independent design tools cannot be used by a MEMS designer.